How to hide patch of mud & oil primer under latex paint

Question

I put a hole in my wall a while ago. I made a patch for it with a wood backing, two drywall patches and spackle in the middle and on top.

I painted over it with CIL (white eggshell latex) paint/primer. Contrary to the claim on the can, the paint did not stick to the spackle. I ended up peeling it off as well as the area around it revealing some of the old chalk paint as well. Apparently painting latex over latex will "activate" the old paint.

I used more spackle to try to smooth out the damage that was done. I then used Kilz Oil Base primer to seal the spackle. I then used the CIL again on the wall. This time it sticks to the wall.

The problem I'm having is that the patch of wall were I primed it with Kilz is noticeable. Essentially there's an area of the wall that is marked with brush strokes from the oil based paint. I tried to paint over with more CIL. I used a bit more than a gallon of CIL on the entire wall and the patch is still visible. This was roughly 4-6 coats on the wall.

What can I do to hide this? I read that latex paint shouldn't be sanded. I tried it and the sand paper won't grab at it. I suppose I could try mudding the wall with more spackle. But I'm worried about doing it on top of latex paint. I'd also likely increase the area of the problem, not to mention I'll have to use oil primer again.

One suggestion I read on a DIY forum was to use Kilz Build Primer. It seems to be designed for this kind of thing. Should it be oil or acrylic? I'm not sure which one to use. Any thoughts on this? Will it work?

I'd hate to bust out the patch of wall or the whole wall because of this so any advice would be helpful.

Answer 1

Yes, you can and should sand latex if you are painting over it. You cannot expect the next coat of paint to grip if it doesn't have a roughed surface to grip to. Painting a glossy or glazed surface is like painting glass - it has no adhesion and will lift right up.

Fresh latex is hard to sand because it hasn't cured yet. You have to wait it out. If it won't sand, it's definitely too soon to overcoat it with anything but itself. (and on that, check the cans for recoat rules). You really need to leave decent curing time between dissimilar products - especially oil over latex.

There is no such thing as paint-primer. Paint companies tell you that to take your money. Their marketing claim is based on painting surfaces which are close to ideal - that is to say, well prepared and primed, with no material variations.

By "material variations" I mean material, color, porosity, chemical differences, anything which might "print through" because the topcoat reacts differently to it. I'm not referring to physical roughness like brush stipple or high spots. The purpose of primer is to bind to the underlying surfaces no matter what they are, seal them, and make them "equal" to the topcoat, so the topcoat applies uniformly and reflects exactly the physical terrain, without visible glitches for any other reason.

Done right, you will not see where wood meets marble, an area was previously painted, or where a cat peed on bare drywall.

You also need to remove surface contaminants which would foul the primer (oil, acids) or prevent adhesion (wax, silicones, linseed oil). In machinery paint, that's the classic 2-cloth wipedown with solvent. Water is a solvent, but too many contaminants are immune to it, so you need to use a chemical solvent or strong soaps, e.g. the classic TSP. You need to get the soap residue off.

Invariably when paint fails, somebody skipped one of these steps.

Why are the oil brush strokes still visible? Is this contamination like acid which is fouling each layer? (remove it). Or is it physical irregularity/bumps (sand it down). A build primer is specifically meant to be sanded. It will leave brush stipple marks far more than a topcoat will, but it's easy to sand.

Answer 2

Are you talking about the shine of the joint compounded area's VS the drywall's texture that is clearly visible after painting?" I've been successful giving my joint compounded areas texture during the second coat of primer. I try to match the texture of the drywall's paper. To achieve this use a cloth or sponge and touch/dab the surface lightly when the primer is tacky. I also tried it during the last coat of joint compound but that can be problematic.